The overall goal of this research program is to provide detailed information on the nature of the actinomycin-DNA complex and thus to provide a molecular basis for understanding the physiological action of this class of drugs. The effects of changes in the structure of the drugs will be investigated in the hope of providing a molecular basis for understanding the physiological activity of the drugs and their derivatives. Nuclear magnetic resonance experiments will provide detailed information on the stability of the oligonucleotide double helices that will be used as model compounds as well as important information on the influence of the binding of the drug on the stability of the miniature double helical complexes. Fluorescence measurements, circular measurements will also be an important means of characterizing the complexes and will be especially important in competitive binding experiments with DNA and oligonucleotides.